/*
 * OREKIT-X
 * Copyright 2002-2008 CS Communication & Systemes
 * 
 * Parts of this software package have been licensed to CS
 * Communication & Systemes (CS) under one or more contributor license
 * agreements.  See the NOTICE file distributed with this work for
 * additional information.
 *  
 * This is an experimental copy of OREKIT from www.orekit.org.
 * Please use the original OREKIT from orekit.org for normal work
 * unrelated to this research project.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you
 * may not use this file except in compliance with the License.  You
 * may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied.  See the License for the specific language governing
 * permissions and limitations under the License.
 */
package ore.tle;


/** 
 * Constants necessary to TLE propagation.
 *
 * These constants are used in the WGS-72 model, compliant with NORAD
 * implementations.
 *
 * @author Fabien Maussion
 */
interface TLEConstants {

    /** 
     * 1.0 / 3.0
     */
    double ONE_THIRD = 1.0 / 3.0;
    /** 
     * 2.0 / 3.0
     */
    double TWO_THIRD = 2.0 / 3.0;
    /** 
     * Earth radius in km.
     */
    double EARTH_RADIUS = 6378.135;
    /** 
     * Equatorial radius rescaled (1.0).
     */
    double NORMALIZED_EQUATORIAL_RADIUS = 1.0;
    /** 
     * Time units per julian day.
     */
    double MINUTES_PER_DAY = 1440.0;
    /**
     * Potential perturbation coefficients
     */
    double XKE    = 0.0743669161331734132; // mu = 3.986008e+14;
    double XJ3    = -2.53881e-6;
    double XJ2    = 1.082616e-3;
    double XJ4    = -1.65597e-6;
    double CK2    = 0.5 * XJ2 * NORMALIZED_EQUATORIAL_RADIUS * NORMALIZED_EQUATORIAL_RADIUS;
    double CK4    = -0.375 * XJ4 * NORMALIZED_EQUATORIAL_RADIUS * NORMALIZED_EQUATORIAL_RADIUS *
                    NORMALIZED_EQUATORIAL_RADIUS * NORMALIZED_EQUATORIAL_RADIUS;
    double S      = NORMALIZED_EQUATORIAL_RADIUS * (1. + 78. / EARTH_RADIUS);
    double QOMS2T = 1.880279159015270643865e-9;
    double A3OVK2 = -XJ3 / CK2 * NORMALIZED_EQUATORIAL_RADIUS * NORMALIZED_EQUATORIAL_RADIUS *
                    NORMALIZED_EQUATORIAL_RADIUS;
}
